Greening works, but cities must plan it smarter

A new study of 138 Indian cities combines satellite vegetation data, night-light data, extreme-aware heat downscaling, and explainable AI to show why urban greening must be matched to humidity, canopy density, and airflow.

Indian Institute of Technology Gandhinagar

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The upper panel illustrates how canopy density is associated with contrasting heat-stress mechanisms. The lower panel conceptualises how these processes interact with urban morphology within a microclimatic boundary.

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Credit: Please credit the Machine Intelligence and Resilience Laboratory at IIT Gandhinagar.

Tree shade is one of the fastest ways to make heat more bearable. It cuts direct sunlight, protects people walking or working outdoors, and remains essential for Heat Action Plans. A new study by researchers from the Indian Institute of Technology Gandhinagar (IITGN) adds a sharper planning question: if greening is so important, why does the same strategy cool some urban areas more reliably than others?

The study, published in Nature Communications, analysed 138 Indian cities from 2003 to 2020 across tropical savanna, semi-arid steppe, and humid subtropical climates. Instead of relying only on land surface temperature, the team reconstructed the Heat Index, which combines temperature and humidity and is closer to how heat is felt by the human body. The researchers used extreme-aware downscaling of temperature and humidity to build one-kilometre Heat Index maps that better capture dangerous high-heat conditions.

The analysis brought together multiple satellite and urban datasets. Vegetation was represented through Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), and Fraction of Absorbed Photosynthetically Active Radiation (fPAR), which respectively capture greenness, leaf-area density, and physiological activity. Night-time lights were used as a proxy for built intensity, while Local Climate Zones helped describe urban form. The team then used explainable AI methods to identify which features pushed the Heat Index up or down and where critical thresholds appeared.

"Greening is essential for climate adaptation, and shade gives people immediate relief," said Professor Udit Bhatia, corresponding author of the study and Associate Professor at IITGN. "Our results show that one-size-fits-all plantation targets miss part of the problem. Cities need greening strategies that are designed for shade, moisture, and ventilation together."

The key finding is that green cover is not a single variable. Canopy structure and canopy activity can affect humid heat differently. Across the 138 cities, the researchers found that vegetation cover and canopy structure were associated with lower model-predicted Heat Index once EVI reached about 0.4 and LAI about 0.05. But high canopy activity, especially fPAR around 0.5 and above, was associated with higher Heat Index in some settings, with the warming signal appearing earlier in humid, dense urban cores.

The reason is physical and intuitive. Trees cool through shade and evapotranspiration. In dry air, evapotranspiration can be strongly beneficial because the released moisture evaporates into air that can still absorb it. In humid and compact neighbourhoods, however, extra moisture can remain trapped near the ground. The result can be a higher Heat Index even though shade continues to provide immediate relief at the street level.

Lead author, Dr Angana Borah, Research Graduate, at IITGN's Department of Civil Engineering, said the findings point to a more practical approach to urban greening. "The question is not whether cities should green. They should. The question is what kind of green, where, and how much," she said. "In dry cities, vegetation can provide strong cooling benefits. In humid and compact neighbourhoods, planners also need to think about airflow and moisture build-up."

For Indian cities, the takeaway is not to slow greening, but to make it climate-responsive. Shade trees, parks, roadside planting, open spaces, and ventilation corridors need to be planned as one system. In humid and dense neighbourhoods, species choice, canopy spacing, pruning, irrigation, and street geometry may all matter because they influence how much shade is created and how quickly moisture can disperse.

This has strong equity implications. The people most exposed to dangerous heat often live or work in dense, poorly ventilated neighbourhoods and have limited access to cooling. Better planned greening can help these communities by improving shade today while reducing long-term humid-heat stress more effectively.

The authors caution that the study works at a one-kilometre city-scale resolution and does not produce a tree-by-tree or species-by-species rulebook yet. Street design, building geometry, irrigation, pruning, and local species traits all matter. “By making model outputs interpretable, explainable AI tools like those used in this study are making complex climate-urban interactions easier for planners and policymakers to understand and act on,” added Professor Bhatia. The approach echoes India’s commitments at the recently concluded India AI Impact Summit 2026 to deploy AI for the Welfare for All, including AI for Social Good. The next step is to connect these city-scale patterns with finer street-level and plant-level data so planners can make more precise greening decisions.

The central message is constructive: trees remain a must-have for heat adaptation, but cities need more than green-cover targets. Under a hotter and more humid future, greening will work best when it provides shade, manages moisture, and leaves space for air to move.

Research team:

Dr Angana Borah, Research Graduate, Department of Civil Engineering, Indian Institute of Technology Gandhinagar

Ms Adrija Datta, PhD Scholar, Department of Earth Sciences, Indian Institute of Technology Gandhinagar

Mr Ashish S Kumar, Department of Civil Engineering, Indian Institute of Technology Gandhinagar

Dr Raviraj Dave, Department of Civil Engineering, Indian Institute of Technology Gandhinagar, and Sustainability and Data Sciences Laboratory, Northeastern University, United States of America

Professor Udit Bhatia, Department of Civil Engineering, Department of Earth Sciences, and Department of Computer Science and Engineering, Indian Institute of Technology Gandhinagar

Paper: Dense canopies reverse the cooling effect of urban greening in humid cities.

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Journal

Nature Communications

DOI

10.1038/s41467-026-72636-w 

Article Title

Dense canopies reverse the cooling effect of urban greening in humid cities

Article Publication Date

4-May-2026

 

A sticky solution to a pesky agricultural problem

New formulation cuts waste, contamination by making pesticides adhere better to plant leaves

University of Waterloo

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High-speed video shows that a new formulation (right) developed by researchers at the University of Waterloo can significantly improve the adhesion of water droplets to various hydrophobic/superhydrophobic plant leaves. (University of Waterloo).

 

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Credit: University of Waterloo

A water-based formulation developed at the University of Waterloo using nanotechnology is both greener and more effective than conventional methods for delivering agricultural pesticides. 

The new solution dramatically improves how pesticides stick to plant leaves – even in wind and rain – minimizing splash and runoff that contribute to costly waste and environmental contamination. 

In early field trials in cabbage plots with an industrial partner in Singapore, the formulation outperformed conventional delivery systems, which use chemicals and solvents to help droplets stick to leaves, by providing better pest control with less pesticide. 

“With our new formulation, the pesticide is dispersed in water,” said Dr. Michael Tam, a chemical engineering professor at Waterloo. “We are spraying water, not solvent, making this approach well aligned with sustainable agriculture goals.”  

How to effectively deliver pesticides to crops is a major challenge in agriculture. Liquids are now typically applied via nozzles and misting sprays and from planes.  

Those methods often fail to deposit pesticides precisely where they are needed. Droplets can bounce off leaf surfaces, drift away in the air, or wash into soil and waterways. 

To help solve those issues, Waterloo researchers carefully altered the surface of particles known as cellulose nanocrystals (CNCs) to create a nanostructured formulation that stabilizes pesticide droplets without chemicals or solvents. The formulation uses carbon-neutral CNCs produced from water, pesticides, and inorganic and metallic nanoparticles.  

“This unique nanostructure significantly enhances droplet strength, suppressing droplet splash during the impact process,” said Tam, noting high-speed imaging confirmed their effectiveness.  

Instead of splashing, fragmenting, or rebounding off leaves, droplets remain intact upon impact, flattening into a pancake-shaped film that adheres strongly. The stabilization method works even when surface tension is reduced by rain and wind, a key distinction from existing technologies. 

Researchers are now seeking industrial partners to scale and commercialize their innovation. 

The study, Self-assembly of cellulose nanocrystals for splash suppression and enhanced pesticide delivery on hydrophobic surfaces, was recently published in the Journal of Colloid and Interface Science and ACS Nano. 

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DOI

10.1016/j.jcis.2025.139564 

 

From pantry to pest control: Garlic kills the mood — for mosquitoes, too

Yale University

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Garlic is not a substance that most people consider an aphrodisiac. It turns out that mosquitoes agree.

In fact, a new Yale study finds that garlic also functions as a de facto birth control for mosquitoes and other winged insects, an insight that could lead to eco-friendly pest control strategies.

According to research by the lab of Yale’s John Carlson, the presence of garlic blocks mating in mosquitoes and a variety of fly species. It’s not the pungent odor that’s a turnoff for these pests, the researchers found, but the taste. And the reason lies in a receptor inside their teeny taste organs. The findings are published in the journal Cell.

“We study flies, including harmless ones like the fruit fly, to try to discover new ways of controlling species that pose danger to humans either by spreading disease or damaging crops,” said Carlson, the Eugene Higgins Professor of Molecular, Cellular, and Developmental Biology in Yale’s Faculty of Arts and Sciences. “In this study, we started with fruit flies and then moved on to other species. And to our surprise, we found a natural compound in garlic that shuts down the mating process in these flies.”

Their method of finding this compound, which they call a “phytoscreen,” could spur new pest control strategies that are environmentally friendly, widely available, and inexpensive. Phyto is Greek for “plant.”

In a Q&A, Carlson explains the role of an enterprising postdoc in initiating this research, how it started with a “fruit fly buffet,” and why Victorian author Bram Stoker had it right about garlic and bloodthirsty creatures.

The interview was edited for length and clarity.

 

What was the impetus for this project?

John Carlson: We have a project in our lab that studies receptors and neural circuits that drive reproductive behaviors in insects, and we use fruit flies as a model organism. Shimaa Ebrahim, an associate research scientist in the lab, had the idea that since fruit flies normally mate on fruits, maybe there’s something in fruits or vegetables that acts as an aphrodisiac and stimulates their mating. So, she went to the supermarket and bought 43 different fruits and vegetables. She made purées from each and put them in Petri dishes for the flies to sample. It was a sort of fruit fly buffet.

What did you expect to see?

Carlson: Shimaa was thinking that at least one of these fruits would produce a big elevation in mating — that it would act as a sort of aphrodisiac. But none of them did. The startling result was that garlic abolished mating completely. It blocked egg-laying, too.

Was it the smell or the taste?

Carlson: We wondered that, too. So Shimaa cleverly placed the garlic purée in a way in which flies could smell it but not taste it, or alternatively in a way that flies could both smell and taste it. It turned out that the taste was the turn-off. Shimaa is a very careful scientist, so she double-checked the findings. She went to a different grocery store to get the same 43 fruits and vegetables and then ran the test again. And she had the exact same result with different bulbs of garlic. Garlic caused a 100% inhibition of mating. We then tested other flies, including tsetse flies, and had similar results.

What exactly is it about garlic that the flies object to?

Carlson: We separated the chemical compounds in the garlic purée and found that one chemical, diallyl disulfide, is the culprit. It prohibits both mating and egg-laying. We were happy to discover that diallyl disulfide is already used in all sorts of culinary products. It’s used in food flavorings and as a component in various nutritional and dietary supplements.

What does diallyl disulfide do to the fly?

Carlson: We found that a sensory receptor in the fly’s taste organs called TrpA1 detects the compound and triggers avoidance behaviors in the flies. This makes sense because TrpA1 can act as a kind of taste receptor. We also found that the garlic activates certain bitter-sensing neurons that have TrpA1 and changes the expression of genes, including one that’s linked to feelings of satiety.

Did it block the mating impulse in both sexes?

It mostly impacted the female fly.

What are the potential broader uses that this work reveals?

There are two. First, we found that garlic deterred the mating and egg-laying of two species of mosquitoes that spread horrible diseases like yellow fever and dengue and Zika virus. Interestingly, it didn’t work at all on wasps, which puzzled us until we learned that wasps don’t have TrpA1 receptors.

The second possible use is that this general approach — testing purées of fruits and vegetables that are cheap and eaten by humans — could be used to find compounds that block other behaviors of other harmful creatures. There’s a vast diversity of compounds in agricultural crops, and Shimaa has invented an easy way of identifying some useful ones. 

Some commercial gardening products already use certain plant-based pest deterrents. How is this different?

Carlson: You can already buy some products that have garlic in them, consistent with our findings that insects don’t like garlic. But what we’ve discovered is the “why.” And now that we know how to look easily for natural compounds that act as insect deterrents, the door has been opened to all kinds of possibilities.

Are there any other lessons you learned?

Carlson: I learned quite a bit about garlic doing this research. It’s inexpensive and grown all over the world. It’s been cultivated for thousands of years, was found in the tomb of Tutankhamen, and has been used for medical purposes since the time of the Roman Empire.

The notion of using garlic to deter blood-feeding creatures was proposed in 1897 by Bram Stoker in his novel “Dracula.” Maybe he was onto something.

What have Yale researchers discovered about garlic and mosquitoes?

For mosquitoes and other flying insect pests, a compound in garlic acts as a sort of birth control. The presence of garlic blocks the mating and egg-laying response in a variety of fly species.  A receptor in the fly’s taste organs detects the garlic compound and triggers this breeding shutdown. Researchers used a “phytoscreen” to test the insects’ reaction to different plants. Phyto is Greek for “plant.”

Haven’t backyard gardeners known for years that garlic can deter insect pests? 

They have. The Yale team has figured out “why.” It’s an important step because researchers now know how to easily identify natural compounds that act as insect repellents, possibly opening the door to new products that are natural, inexpensive, and readily accessible.  

What other fly species was garlic effective on?

Garlic deterred the mating and egg-laying of two species of mosquitoes that spread diseases including yellow fever, dengue, and Zika virus. It was also effective on tsetse flies and fruit flies.

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Journal

Cell

 

Brewer’s spent grain transformed into biodegradable paper: A circular economy solution developed in Ecuador

Escuela Superior Politecnica del Litoral

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Graphical Abstract – Alkaline Pulping Process and Economic-Environmental Impact

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Credit: Alcivar-Reyna et al. / ESPOL

The growing global demand for paper continues to exert pressure on forest resources, while numerous industries generate large volumes of waste with high potential for valorization. In this context, researchers from Ecuador conducted a study demonstrating the technical and economic feasibility of producing biodegradable paper from brewer's spent grain, an abundant byproduct of both traditional and craft beer industries.

Brewer's spent grain is the solid residue remaining after the mashing process in beer production. Although it is typically used as animal feed or discarded, this material features a composition rich in cellulose, hemicellulose, and lignin—key components for papermaking. Harnessing this waste represents a strategic opportunity to transform an environmental problem into a value-added industrial resource.

From Industrial Waste to Sustainable Raw Material

The study evaluated the feasibility of converting brewer's spent grain into paper through an alkaline pulping process using sodium hydroxide (NaOH). For this purpose, residues were collected from various beer styles brewed in Guayaquil, Ecuador, ensuring the representativeness of the analyzed material.

The experimental process included several stages: drying and milling the spent grain, alkaline digestion in two controlled thermal phases, washing, sheet formation, pressing, drying, and final characterization of the obtained material. Subsequently, the physical, mechanical, and morphological properties of the produced paper were analyzed.

The results confirmed that the obtained fibers have suitable dimensions for forming stable paper structures. Microscopic analysis revealed fiber diameters ranging from 10 to 61 micrometers, values consistent with cellulosic materials used in the conventional paper industry.

A Biodegradable Paper with Properties Comparable to Commercial Grades

One of the most significant findings was that the produced paper achieved mechanical properties close to those of commercial papers. Tests showed a maximum tensile strength of 2.26 MPa and an average tear strength of 2.19 N, key indicators of structural durability.

Furthermore, the material exhibited low porosity and a high basis weight, characteristics that suggest potential applications in sustainable packaging, biodegradable products, and alternative materials to traditional wood-based paper.

These results demonstrate that agro-industrial waste can be transformed into functional materials without compromising the mechanical performance required for real-world applications.

Circular Economy Applied to the Brewing Industry

Beyond material development, the research focused on evaluating its economic viability within a circular economy model. Initially, production costs at the laboratory scale were high; however, prospective analysis showed that recovering over 80% of the sodium hydroxide used could reduce the cost to approximately $3.28 per square meter, bringing it closer to industrial competitive levels.

This approach enables closing material loops, reducing waste, and decreasing reliance on virgin raw materials from forest resources. Valorizing brewer's spent grain not only reduces environmental impacts associated with its disposal but also opens new economic opportunities for local industries.

Sustainable Innovation from Latin America

The study aligns with global trends aimed at replacing linear production models—based on extract, produce, and dispose—with circular systems that prioritize reuse and comprehensive resource utilization.

The food industry, particularly brewing, generates large volumes of byproducts rich in lignocellulosic biomass. Transforming them into bioproducts represents a key strategy to reduce industrial environmental footprints and diversify raw material sources across multiple sectors.

Developing non-wood alternatives for paper production also helps reduce pressure on forest ecosystems, promoting more resilient and sustainable supply chains.

Challenges and Next Steps

Although the results validate the technical feasibility of the process, researchers identified significant challenges for future stages. These include improving material homogeneity, reducing ash content, and optimizing parameters for industrial scale-up.

Future research phases could focus on integrating chemical recovery processes, energy optimization, and environmental life cycle assessment (LCA) to consolidate the sustainability of the process at scale.

Science with Environmental and Social Impact

This work demonstrates that scientific innovation can emerge from everyday, local problems, generating solutions with global impact. Converting brewing waste into biodegradable paper not only proposes a technological alternative but also a conceptual shift in how industrial waste is understood: waste can become strategic resources within a circular economy.

This research opens the door to the development of new sustainable biomaterials in Latin America and highlights the potential of academic collaboration to drive environmental solutions based on applied science.

In a global landscape that demands reduced emissions, minimized waste, and optimized resources, initiatives like this show that the transition toward more sustainable production systems can begin by harnessing what was once considered mere waste.

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Journal

Green Technologies and Sustainability

DOI

10.1016/j.grets.2026.100345 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Feasibility of producing biodegradable paper from malt bagasse: Bridging waste valorization, material performance, and circular economics

Malt Bagasse to Biodegradable Paper: A Circular Economy Approach (IMAGE)

Escuela Superior Politecnica del Litoral

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Graphical Abstract: Process Flow from NaOH Digestion to Sustainable Paper Production

 

Sustainable Diversification & Industrial Symbiosis

Credit

Alcivar-Reyna et.al.

 

Study Reveals How Strawberries, Raspberries Were Ambushed By Fungal Parasites

North Carolina State University

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Microscopic image of the fungus powdery mildew that infects strawberries. The round structures are survival structures that help the fungus survive over the winter. In this image, these structures are releasing sac-like bodies that contain the spores. Fine, thread-like filaments surrounding them help the structures attach to the plant. Differences in color reflect different stages of development.

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Credit: Andrew Paul

Plant diseases often arise when the pathogens that cause disease are introduced into new territories where native plants don’t recognize the pathogen and therefore may have minimal defenses against it. But there’s another option.

How often does the reverse happen: a plant gets introduced into areas where the pathogen already lurks in the soil – targeting other plant hosts native to the area – and then “jumps” to infect the newly introduced plant?

A new finding regarding strawberries and raspberries encumbered with powdery mildew disease in North America, Europe and Asia suggests the latter happens more frequently than we thought.

The study pinpoints the ancestral history of powdery mildew disease caused by different but related fungi. The findings could aid the understanding of how plant diseases arise.

“We have this general idea that a pathogen originates in one spot, and then it spreads throughout the world. But what we’re showing here is that’s not always the case,” said Michael Bradshaw, assistant professor of plant pathology at NC State and corresponding author of a paper describing the research.

“What happened in this case is that the pathogen co-evolved on one host pretty closely related to strawberries or raspberries over millions and millions of years, and then when strawberries or raspberries were introduced to the same area, the pathogen jumped hosts.”

As its name suggests, powdery mildew disease causes a white, powdery substance to cover host plants, stealing nutrients and retarding photosynthesis while keeping the host alive. Different species of this fungus affect different plants; wheat, hops, grapes and blueberries, among other plants, have been detrimentally affected by powdery mildew.

In the study, Bradshaw and his colleagues examined historic and modern plant leaves plagued by powdery mildew. The collection included 70 samples from North America and Europe; some were more than 100 years old.

The researchers performed genetic testing on fungal samples to trace the history and spread of powdery mildew disease. In North American samples, the powdery mildew Podosphaera shepherdiae infects strawberries, while in Europe and Asia a related but different powdery mildew, Podosphaera fragariae, plagues strawberries.

“If you’re looking under the microscope at these pathogens, the one that infects strawberries in North America looks very different from the one that infects strawberries in Europe,” Bradshaw said. “To date, the powdery mildew from Europe still hasn’t been found in North America, and vice versa. So that’s kind of like the smoking gun: It’s not one pathogen spreading throughout the world. These pathogens seem to be already present in these different places.”

The study also used molecular clock techniques to show that these two powdery mildew pathogens affecting strawberries on different continents split off from each other more than five million years ago.

Both North American and European powdery mildew pathogens infect plants in the rosaceous family, which includes flowering plants related to roses, strawberries, raspberries, peaches and pears, among others.

“These two pathogens were actually described over a hundred years ago, one of which was described on a plant native to North America,” Bradshaw said.

Bradshaw believes these findings – showing that pathogens can jump from a native plant to a newly introduced plant – can be generalized for most plant pathogens.

He also predicts these pathogens will eventually spread the more traditional way – by traveling on plant material brought across the Atlantic Ocean – and attempt to live and thrive on a new continent.

“Will these two different organisms mate with each other? Will they infect strawberries more when they’re both on the plant? Or will they compete with each other for the host’s resources and cancel each other out?”

Bradshaw also plans to study more about the powdery mildew on wine grapes and wheat, two important crops affected by other powdery mildew species.

The paper, “Global Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases,” appears in Proceedings of the National Academy of Sciences. Funding was provided by the National Science Foundation under award number 2402193 and by the U.S. Department of Agriculture’s National Institute of Food and Agriculture Research Capacity Fund (HATCH), project award number 7006142. This work was part of the Chancellor’s Faculty Excellence Program in the Emerging Plant Disease and Global Food Security Cluster.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2536984123 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Global Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases

Article Publication Date

8-May-2026